Today Petrona doesn’t smile. The smile that overwhelms in the face of adversity, that endears hope and devours pain, is missing. We all feel it.

Today her pain transcends time. Sergio’s treatment seems futile; the pain is drawing Petrona back to the moment in the fire, when the insufferable pain she couldn’t feel then, and her life of pain in the subsequent months, was beginning to engulf her. Sergio, however, is unfazed. “When I come next time, there will be a very great surprise for you!” he says in Tzotzil, Petrona’s Mayan dialect. He translates his words into French and then English to engage hope in not only Petrona, but all those in the room who come from abroad to volunteer their help.

Petrona is a fourteen-year-old Mayan girl who lives in San Cristobal de las Casas in Chiapas, Southern Mexico. She has been receiving treatment from Sergio Castro for three months, and has at least another three months before her wounds are healed. The burns to her right arm and side were caused when fumes from treated wood used to fire a traditional Mayan steam bath, called a temezcal, caused her to pass out, and fall into the temezcal fire. There she lay, unconscious for half an hour.

The wound that has laid bare the bone along the length of Petrona’s arm is a grim sight. It has improved due to Sergio’s visits, as has the prospect of Petrona retaining her arm, which the local hospital had given up as a case for amputation.

For Sergio Castro, apathetic hospitals and bureaucracy have created a lifetime’s work, filling the holes of social indifference created by these establishments. For forty-four years he has given his work and compassion to the Indian population of Chiapas – building twenty-two schools, providing drinking wells, improving agricultural practices and treating hundreds of burns victims and other medical cases using lifesaving medical practices learned from books or from time spent with Mayan shamans of the area.

Castro came to Chiapas in his early twenties from the northern state of Chihuahua to spend a year undertaking field studies in the village of Tenejapa as part of his agricultural engineering degree. He has remained here ever since, after a moment many years ago when, while walking in the hills, he stumbled upon a boy in a village who had been badly scalded. “It was a situation where something just had to done. The boy was badly burned about the face, arms, and chest and was in incredible pain. After bathing the boy in cold water to relieve the sting of the burn, I began to treat him with Aloe Vera that grows in great abundance in the hills, and gradually the burns healed. From then until now this is what I do: I help, I cure and then I take another”.

He is a remarkable figure amid the revolutionary, political and religious climate of “Indigene Development” in Chiapas. Zapatistas, pro-government factions, religious evangelists and international NGOs all vie for the righteous high ground of having the “Indigenes” best interests at heart. All are high profile and largely ineffective.

Sergio Castro works with very little funding, nor is he well known, apart from the adulation and affection he has gained among the Indian population. Part of his funding is generated by a museum he has created from years of collecting Indian costumes, Mayan artifacts, hunting trophies and all manner of other oddities. One room of the museum is dedicated to his work with burns victims, with an entire wall covered in photographs of appalling and unbelievable burns. The room is essential for shocking a few pesos from the pockets of tourists to help with his ongoing care work.

The hunting trophies are prized animal heads, hunted during his earliest years in Chiapas, when Castro spent fourteen years living with the Lacandones people in the remote jungles of Southern Mexico. In this time Castro learned the Mayan language and custom, immersed in daily routines of hunting, farming, ceremonies, etiquette and the art of survival. The effect of Mayan teachings is obvious in Castro’s demeanor; at one moment he is powerful and eloquent, the next humorous, tranquil and content in his existence. He loves to joke and laugh about living life, a very Mayan disposition born out of a tough life. People die young from disease, malnutrition and overwork, or, as with Petrona, are badly injured in some unfortunate accident. Sergio has lived his life alongside death and tragedy, and he knows the gift of each moment lived. This attitude informs his work with vulnerable people.

In Castro’s makeshift mobile clinic, a VW Kombi, we chugged our way through the mountains of Chiapas. There was always good humour in the van. Domingo, Sergio’s friend and assistant for so many years they’ve forgotten the number, bears the brunt of much of Sergio’s sharp wit. Along with Domingo, the team of cowboy medicos included a French tree surgeon named Dominic and an Italian train conductor named Stephano. Both come to Chiapas each year for a number of months to administer Sergio’s special brand of humility, humour and care to the locals.

One of our regular patients was a boy named Carlos, who had been badly scalded down his chest and arm. It was a traumatic time for the boy, and on our visits a bawling Carlos invariably greeted us. The ensuing pain of changing the dressings was close to unbearable for the three-year-old.

To add a little cheer to the ritual of tears and weeping wounds, Sergio always brought along small treats of chocolate, fruits and sweet cakes. As with all Sergio’s patients, Carlos would eventually be put at ease by the warm, joking manner in which he went about his work. Occasional outbursts of “no quiero, no quiero,” (‘I don’t like it’) when the dressing stuck to the skin would be allayed by Sergio’s soothing and tender “Cun cun niño, cun cun,” (‘I’m here, child’).

After dressing Carlos’s burns one day in Chimula, Sergio announced that we would be moving on to see a badly burned boy he had heard about, who lived a further two hours’ drive into the mountains. It was a delightful mornings’ drive, winding through clear mountain air scented with pine and the earthy aroma of dried milpa crops. It was a stark contrast to what awaited us.

On arrival we were lead by the boy’s father into one of the mud and thatch huts that made up the family compound. The room was pitch black as we entered, until the father switched on the single light bulb that illuminated the room. Before us, laid on a rattan mat over the dirt floor was a body, whimpering softly.

Sergio and his father helped the figure up. The sight was quite unearthly. His whole face was a bloody, charred abomination. The flesh of his eyelids had been scorched shut, as had his lips. His name was Lorenzo Gomez and he was fourteen.

As Sergio set about his work and the rest of us struggled to deal with boy’s desperate situation, his father explained what happened. “My son is an epileptic and during a seizure he fell into the fire. He was discovered a few minutes later by my wife who wrenched him out”. He went on to explain that Lorenzo had also suffered the apathy of a local hospital. “I took my son to the hospital in Tuxtla straight away. He spent two weeks there, but he did not receive any treatment; his condition became much worse and he couldn’t even eat.”

After some hours Sergio had removed a lot of the charred tissue, and had managed to open Lorenzo’s eyes and mouth. He was now a more bloody sight than when we had arrived, but the burns had been cleaned and somehow he looked more alive. I detected a slight smile; being able to see and eat again had obviously gladdened him.

The events of our next visit were something we foreign onlookers were at pains to fathom. On our first visit Sergio had requested that the father try to arrange alternative accommodation for Lorenzo in Chumula, just half an hours’ drive from San Cristobal de las Casas, where he would be able to treat Lorenzo more readily. However, on our return the father said that he could not afford the time or money to accommodate Lorenzo in Chumula. It was now the season to plant milpa, the crop that would be provide family’s income. He also requested that Sergio not visit anymore, and that he had decided to seek the help of a local healer. Sergio had no choice but to honour the man’s wishes. He explained to the van of gob-smacked gringos, “The father must always make his decisions for the good of the whole family”.

On the day of my last visit to see Petrona, I was full of dread that I would not see her smile, and the enduring memory I would have of her would be her pain. In the days since our last visit I had thought of very little other than the desperate reality of her life; the psychological torment of laying next to a nearly dead and disfigured arm for so long, with many months of treatment ahead and no guarantee of successful recovery.

We entered the room behind the family’s fruit and vegetable stall and were immediately greeted by her blinding smile. Our spirits lifted accordingly, as Sergio and his team went to work with the efficiency developed over many visits. Unusually upbeat, there seemed to be a special sparkle in her eyes this day, as she and Sergio joked and made light of the more painful moments. Petrona’s mother came into the room and laid a pair of shoes next to her daughter’s bed; they looked at each other and again great smiles beamed. It became apparent this was a special day indeed. Petrona would leave her bed and walk outside for the first time in three months. Bound in metres of bandages that gave her an absurd, mummified look, Sergio and her father helped her from her bed. Movement was clearly painful and foreign now, but she endured it happily. I was immediately struck by how tiny she was. Since meeting her I had only seen her laid out on the bed, and so, only affected by her immense spirit, had imagined her to be much taller.

Her whole family had gathered for this grand occasion; her three sisters fussed about, helping her into her shoes. Then, timidly, she took her first steps towards the door, and stepped out into the brilliant Chiapas sunshine. It was a moment of pure euphoria, collectively felt. This was a moment of hope that would give her the courage to continue fighting.

Before we left her to enjoy the sun, I asked her what she thought of Sergio. She simply replied “I am very pleased he is here, he makes me smile”.